For regenerative treatments, native tissue segments of human or mammalian origin have been used clinically as such or after decellularizing or treating with cell-fixing agents such as glutraldehyde. It is advantageous in the regerative treatment to use a regeneratable hybrid tissue prepared by injecting autologous cells of the recipient into the tissue and allowing the cells to grow therein. This method may not only avoid recipient's immune response to the transplanted tissue but also promote autogenesis of the transplanted tissue.
In the preparation of the regeneratable hybrid tissues, a cell suspension is injected manually using a syringe. However, many transplatable tissues have elastically deformable surfaces and, therefore, it is not easy even for skilled operators to pierce the tissue with a syringe needle accurately and precisely in position.
A method and device adapted for injecting medical solutions and other liquid into such elastically deformable tissues is disclosed in JP-A-03322568 and JP-A-200146500. The method and device injects a liquid while vibrating the needle ultrasonically.
In the preparation of the regeneratable hybrid tissues, it is imperative to inject a cell suspension into the tissue in a volume in the order of microliters at many target positions space apart a distance in the order of micrometers with a distribution density which may often reach up to several thousands per square centimeter. It will be impossible in practice to prepare such a regeneratable hybrid tissue with the known method and device by simply vibrating the needle.
There is another problem associated with the known method and device. Regeneratable hybrid tissues are often prepared from pulsating mammalian heart walls or relatively thin blood vessel walls. Since these tissues may move back and forth in the direction perpendicular to the general plane of the tissue, it is difficult to locate the vibrating needle tip at a desired depth and the needle tip may often penetrate through the tissue thoroughly by the vibration.